Photo 3/15 | 2006 Gmc Sierra 2500 Burnout | Shortly after our interview, we found John and his
truck doing this. At roughly 7,200 pounds, a 92-mph
trap speed in the eighth-mile confirms this nasty
GMC is making at least 750 hp at the wheels.

Photo 4/15 | S400 Turbocharger | An 80mm S400 (S480) serves as the atmospheric turbocharger in the compound arrangement found under the
hood. The top-notch compound-turbo system came from Wehrli Custom Fabrication in Sugar Grove, Illinois.

Photo 5/15 | 6 6l Lbz Duramax Engine | Sitting in the factory turbo’s location is a 68mm, Stage 2 Garrett PowerMax. The
variable-geometry GT4094VA charger is responsible for getting things started at low rpm
(before the big S480 begins to stir). Both turbos combine to make a little less than 70
psi of boost at full tilt.

Photo 6/15 | Drivers Gauges | Inside, the driver and passengers are treated to Katzkin leather seats and one of the cleanest interiors
we’ve ever seen. Like so many other diesel owners, John relies on an Edge CTS monitor
mounted on the dash to keep an eye on all the typical powertrain necessities. Two Auto Meter
Ultra-Lite II series gauges were sourced from Randall’s Performance and installed along the A-pillar
to keep tabs on boost and EGT.

Photo 7/15 | Allison 1000 Transmission | Well before John’s quest for power got out of hand, he addressed the six-speed Allison 1000. With
the help of Flynn’s Shop, a GMax 6-pac kit, TransGo shift kit, and 1058 torque converter from Sun-
Coast were installed. From there, the commercial-grade automatic was ready to handle big torque
and horsepower.

Photo 8/15 | Traction Bar | Keeping the rear planted is a set of One Up Offroad’s short-gusset traction bars. One Up’s bars are
well known throughout the industry for being unmatched in functionality, performance, and reliability.

Photo 9/15 | Fass Fuel Sump Kit | A FASS fuel sump kit was installed in the factory tank to rule out any low fuel issues through the
pickup and allow fuel to gravity feed to the lift pump.

Photo 10/15 | Fass Fuel System | A ½-inch fuel supply line connects directly to a 220-gph Titanium series
FASS system. From there, a constant 15 psi of fuel is sent to a 10mm stroker
CP3 pump from Motorsport Diesel.

Photo 12/15 | Chromoly Tie Rods | These burly, chromoly tie rods came from Exaxt out of Canada. Other bulletproof
parts added to the IFS front end include Exaxt pitman and idler
arms, as well as a practically indestructible 1.75-inch-diameter chromoly
centerlink.

Photo 13/15 | Dsps Switch Under Dash | A DSP5 switch hidden under the
dash allows John to flip through an
assortment of custom EFILive tunes on
the fly. Duramaxtuner.com’s Nick
Priegnitz is responsible for the truck’s
solid horsepower numbers, its firm
yet smooth shifting, and how civilized
the Sierra is on the street.